What is required when the traffic light turns to yellow?
There is a bit of misinformation online about what the actual requirements are. A number of websites that I’ve reviewed say that you can receive a traffic ticket if a traffic light turns red while you are driving through the intersection. In most of the United States, this isn’t true.
The laws governing when a driver may enter an intersection on a yellow traffic light aren’t the same in every state. Most states have a permissive yellow traffic light law, while others have a restrictive yellow law, of which there are two variations.1
Permissive Yellow Law
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- A driver can enter the intersection during the entire yellow interval and be in the intersection during the red indication as long as the vehicle entered the intersection during the yellow interval. Under permissive yellow law, an all-red clearance interval must exist as a timing parameter to ensure safe right-of-way transfer at an intersection.
Restrictive Yellow Law
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- In one variation, a vehicle may not enter an intersection when the indication is yellow unless the vehicle can clear the intersection by the end of yellow.
- In the other variation, a vehicle may not enter an intersection unless it is impossible or unsafe to stop.
After Yellow
After the yellow light, there is sometimes a time period – called the “red clearance interval” – between the time that the red light comes on and when the green light comes on for cross traffic to move.
Some Yellows are shorter than others
The Institution of Transportation Engineers has an equation for determining how long a yellow change light should be on.
So what does a driver do when the light turns yellow?
Do I stop or do I continue on through? The area where you may be undecided is called by some the “dilemma zone” and it’s where thousands of crashes occur each year in the United States.
Eight states have restrictive yellow laws. In those states, if you are in the intersection when the light turns red, you can be ticketed for breaking the law – and you might be caught by a red-light camera. The restrictive states are Iowa, Michigan, Mississippi, Nebraska, New Jersey, Oregon, Virginia, and Wisconsin.
In those states, if you can stop without hard braking, then stop when the lights go from green to yellow. If you can’t, then continue on through the intersection – there shouldn’t be a need to accelerate.
Even in the other states, that’s probably a prudent approach.
- Traffic Signal Timing Manual – Office of Operations, Federal Highway Administration (accessed June 10, 2019) This document has been superseded by a later edition, but the descriptions for the yellow law aren’t as good in it.
